[Mailman-Users] Blocking entire domains

[Mark Sapiro]

Troy Buffum wrote:

>On 7/8/06, Martin Dennett (Gmail) <md6969 at gmail.com> wrote:
>> Admin Screen > Privacy Options > ban_list
>>
>> Add:
>> ^.*@123abc.com
>
>I never would have thought of using a wildcard entry for this purpose.  I 
>wonder if you could "invite" an entire domain with this command?  Not that 
>anyone would be crazy enough to want to, just food for thought.


The ban_list and all the *_these_nonmembers entries accept regular
expressions (not exactly 'wildcards' see
<http://docs.python.org/lib/re-syntax.html> for syntax) as indicated
in the 'details' for these entries.

And no, you can't use a regular expression for an invitation as it
could generate an infinite number of addresses. E.g., the number of
syntactically valid email addresses in a domain is a huge number even
if you limit the length, and there is no way to know which of these
might be in the very small proportion that are valid without sending
mail to all of them.

Even if you limit the local part to no more than 12 characters and
allow only case insensitive letters, digits, dash, underscore and
period, there are over 10^19 combinations. If you could test these for
validity at 1 per microsecond (1,000,000 per second) it would still
take over 300,000 years to test all of them. In fact, it would
probably take that long just to generate them.

Theres no limit to what one can think up with a little 'food' :-)

-- 
Mark Sapiro <msapiro at value.net>       The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan